Chemistry Reference
In-Depth Information
CHAPTER
42
Tin
ELENA A. OSTRAKHOVITCH AND M. GEORGE CHERIAN
ABSTRACT
compounds are neurotoxins. Triethyltin can cause en-
cephalopathy and cerebral edema. Severe dermatitis
has been described in workers exposed to tributyl-
tin and painters applying formulations. Tributyltin is
widely used as an antifoulant in marine paints to pre-
vent any growth on ocean vessels. However, the use
of tin-containing paints for smaller marine vessels is
restricted in many countries.
Organotin compounds can penetrate cell membranes
because of their lipophilicity and cause damage to cell
membrane, interrupt oxidative phosphorylation, and
damage mitochondria. They can inhibit synthesis of
heme oxygenase and can be immunotoxic and geno-
toxic. There is no defi nite evidence that inorganic or
organic tin compounds can cause carcinogenic or tera-
togenic effects, although in a few studies effects have
been reported. Tributyltin and triphenyltin are impli-
cated in endocrine disruptions, and hence, cause repro-
ductive failure in marine organisms.
Further detailed information on tin compounds can
be found in reviews by Klevay (2000), Hoch (2001),
and WHO documents (WHO, 1999; 2001; FAO WHO,
2005).
Tin is not an essential metal and is widely used in
industry. In nature, it occurs both in inorganic and or-
ganic forms. The gastrointestinal absorption of soluble
tin salts is only a few percent of the ingested dose. In
chronic exposures, bone is the major storage organ for
tin, and its biological half-life in bone is approximate-
ly 100 days. The excretory routes of tin compounds
may vary depending on the type of tin compounds
and the mode of exposure. Most of the inorganic tin
compounds are nontoxic because of their low solubil-
ity and absorption. In workers who inhale tin oxide,
it accumulates in the lung and causes “stannosis,” a
benign pneumoconiosis without any tissue reaction or
pulmonary dysfunction.
Although insoluble tin compounds are nontoxic,
soluble tin compounds can be toxic. Oral administra-
tion of 45 mg/kg of stannous chloride can induce vom-
iting and diarrhea in cats. In human, high intakes of
inorganic tin compounds can cause abdominal pain
and anemia. Inhaled tin hydride gas can cause dam-
age to nerves. Epidemiological study shows a positive
relationship of increased tin intake to a decrease in
copper status, changes in cholesterol metabolism, and
ischemic heart disease.
Tin can be converted by chemical and biological
reactions in the environment to form more toxic or-
ganotin compounds. Short-chain alkyltin compounds
such as trimethyl and triethyl tins are well absorbed
from gastrointestinal tract, whereas long-chain alkyl-
tin compounds are not much absorbed. The toxicity
of organotin compounds differs, depending on their
physicochemical properties. Alkyl and aromatic tin
1 PHYSICAL AND CHEMICAL PROPERTIES
Tin, Sn: atomic weight, 118.69; atomic number, 50;
density, 5.8-7.3; melting point, 231.9°C; boiling point,
2602°C (
Handbook of Chemistry and Physics
). Tin exists
in three allotropic forms: white metallic, tetragonal
(tin white), and white rhombic (tin brittle), and when
tin is cooled below 13.2°C, it is converted to allotropic
form called gray tin or
α
-tin, cubic. Tin is a metal that
